Electronic signal storage system



1956 N. 1. KORMAN EI'AL 2,766,399

ELECTRONIC SIGNAL STORAGE SQSTEM Filed April 7, 1953 INPUT I SIGNAL AMPLIFIER i l DEFLECT'ION W CONTROL SAW TOOTH 9 SWEEP GENERATOR OUTPUT INVENTORS,

NATHANIEL I. KORMAN BY I JOHN R. FORD 2,766,399 Patented Oct. 9, 1956 ice;

ELECTRONIC SIGNAL STORAGE SYSTEM Nathaniel I. Korman, Rancoeas, N. J., and John R. Ford,

Narherth, Pa., assignors to the United States of Ameriea as represented by the Secretary of the Army Application April 7, 1953, Serial No. 347,202

3 Claims. (Cl. 315-23) This invention relates to a storage type tube wherein the storage of a signal is achieved in such a manner that a high fidelity output signal is obtained.

fie invention utilizes the property of materials having high dielectric characteristics which permit them to retain an electric charge when their surface is scanned by an electron beam. The electric charge acquired by the storage element is utilized to induce an output signal proportional to an input signal impressed upon the electron beam. The charged condition of the storage member will permit an accurate reproduction of the original signal to be released thereform by a subsequent scanning operation.

Various methods of storing a pattern of information upon the surface of the storage member may be used. A widely used method of creating a pattern has been to modulate the intensity of the electron beam while it is scanned across the storing element at a constant velocity. This method has been found undesirable for certain uses of the device.

The present invention proposes to utilize the most effective means for applying the desired information pat tern to the storage element with the end in View of obtaining a high signal-to-noise ratio and the recording of a pattern which will produce a high fidelity output signal.

It has been found that a desirable manner of operation for the apparatus is to combine two methods of recording the input signal. To do this the signal frequency is divided into a high and low band. One method most suit able for recording the higher frequencies is used for that purpose and another method most suitable for recording the lower frequencies is used in combination to produce high quality output signals throughout the whole spectrum of frequencies embraced by the input signal.

It is a primary object of the invention to provide a storage tube which functions with high accuracy and sensitivity.

A further object of the invention is to provide a storage tube which utilizes a combination of the best methods of storing a signal to produce an apparatus of high sensitivity capable of producing high fidelity output signals.

A still further object of the invention is to provide a storage tube having maximum storage capacity in discernible units of information per unit of sweep length.

Other objects and features of the invention will more fully appear from the following specification taken in connection with the appended claims.

To provide a better understanding of the invention a specific embodiment thereof will be described in connection with the accompanying drawing in which the invention is illustrated diagrammatically some of the conventional units being illustrated in block diagram.

While any suitable structure may be used to provide the required storage facility for the invention, the cathode ray tube forms a convenient piece of apparatus with which the invention may be practiced.

In the embodiment of the invention to be described herein the cathode ray tube 1 is utilized having an envelope 2 inclosing an electron gun 3. The gun 3 is supplied with the necessary power and beam forming means, not shown, to provide an electron beam 4 which is directed upon the face 5 of the tube 1. Electrostatic beam deflecting means indicated, generally, at 6 is provided for controlling the beam.

The face 5 of the tube may consist of any suitable material having high dielectric properties capable of storing a pattern of electric charge. However, it has been found that the conventional type of glass used for cathode ray tubes is a very suitable material. The face 5 will be referred to as the storage element and receives a charge upon its inner face as a result of the sweeping motion of the beam 4. The outer surface of the face 5 is provided with a conducting layer or plate 7. This plate 7 may be in the form of a coating applied directly to the tube surface or may be a metallic plate held in close proximity to the surface. The plate 7 constitutes an electrostatic coupling element for the electric charges impressed upon the storage element and has an output electrode which may be connected to any desired utilization circuit.

The phenomena connected with the storage of an electric charge upon the storage element by the beam 4 is well known and will not be set forth herein.

The beam 4 may be swept across the storage element in any suitable manner such as by means of a saw-tooth sweep generator indicated at 8. The output of this generator is connected to the circuit 9 leading to the plates 10 of the beam deflector 6. The plates it) constitute the basic deflecting means for the beam 4.

The signal to be stored, desirably, is amplified in an amplifier 11 and fed to an input circuit including means to divide the signal into a high frequency component and the lower frequency component. Such means may be the equivalent of a high and a low bandpass filter system. The high frequency passing means is represented in the drawing by a differentiating condenser 12 the output of which is connected to the circuit 9. The input circuit of the device is completed thru an impedance 13 and to ground. Thus, the high frequency component of the input signal is impressed upon the plates 19 of the tube 1.

The low frequency component of the signal is passed through the low frequency passing means which is represented by an impedance 14 and may then be conducted to a lateral deflection controlling system 15 wherein it may be given a pulsed conformation or in any suitable manner prepared for application to thelateral deflecting plates 16 of the unit 6. The unit 15 may, however, be dispensed with.

Suitable means, not shown, may be provided for properly timing the application of signals and the pulsing rate with the timing of the sweep of the beam 4. A pulse from the sweep generator 8 may be used to trigger the application of a signal to the input.

It will be apparent from the above description that the signal is stored upon the tube face by a combination of two storage methods. The higher frequencies which pass thru the condenser 12 are applied directly to the sweep circuit including the plates 10. This application of the signal results in modulating the sweep voltage upon the plates and consequently the velocity of the sweep of the beam 4. By varying the velocity of the beam, the value of the charge imparted to the storage element is controlled in accordance with variations in the high frequency input signal. This recording of the signal results from the property of the storage element to acquire a charge which is a function of the velocity of the constant intensity beam 4.

The invention is particularly useful where the spec- 3 trum of the input signal'embraces a relatively wide range of frequencies and its use results in an accurate high fidelity output signal. This: high quality results from the factthat the high: frequency; portions-of. the signal are more accurately stored by the use of velocity modulation whereas the lower frequency. portions of the signal spectrurnare more effectively. stored by the deflection modulation-method. Acombination of thesetwo methods results in producing high-fidelity,high power output signals.

As above stated, the'lower frequency components are passed to a device which conditions the signal to act as a-lateral deflecting influence upon the beam 4 by reason of impressing the signal thus prepared. upon the lateral deflection:plates 16-of the tube 1. It has been found that deflection modulation is' most effective andeflicient when functioning in the lowerfrequency range. In this way the high overall efliciency above referred to is achieved.

Recording a signal upon the storage'surface by deflection modulation is an accepted procedure and therefore the details of the phenomena'will notbe set forth herein; It is snfficient to say that a true representation of the signal is impressed upon the storage element in the form of a pattern of electric charges which yield a high fidelity output signal.

When it is desired tomerely store a signal for an appreciable length of time and then reproduce it, the same apparatus may be employed. When the invention is thus employed the signal isstored upon'the tube face 5 as above described but the signal is not immediately removed therefrom. Subsequently, however, the signal may be utilized by again'scanning the storage element with a constant velocity beam. The outputsignal will thus be made available for use in the load circuit.

We claim:

1. An electronic signal storage system comprising a storage tube including an evacuated envelope having a glass face, an: electron gun having means. to provide a constant intensity beam directed at said glass face, a first beam deflecting means in said tube operable to produce a basic scanning path, a second beam deflecting means to produce a lateral deflection from said path, an input circuit containing a high frequency bandipassing means and a low frequency band'passin'g means, a saw-tooth sweep generator operable to sweep said beam in said basic scanning path, a connection from said high frequency band passing means-to'the output of said sweep generator and to the basic beam deflecting'meansin staid tube, a connection fromsaid-low band passing means to said second beam deflecting means and aconductive output plate capacitatively coupled to said glass tube face.-

2. An electronic signal storage system comprising a storage tube havingan electron gun adapted-to provide a beam of constant intensity, a storage element of high dielectric in the tube disposedin the path of said'beam, a first beam deflecting meansein said tube, a second beam deflecting means in said tube operable to deflect said beam at right angles to the deflection path of said first means, a signal input circuit, high and low frequency band passing means connected to saidinput circuit, a connection from the outpntrof said-high:bandtpassing means to the first beam deflecting means, means also connected to said first bearn= d'eflectihg-mea-ns acting to'sweep' the beam across said storage: elem'entwith constant velocity, a connection from said' l'owbandpassin-g means to a deflection control unit. externahofsaid. tube having means to convert the low frequency signal to an amplitude suitable for deflection modulation, 2: connection from said external deflection control to said second beam deflecting means in said tube and a conductive output plate capacitivelycoupled to-said: storage element acting to conduct an output signal to a:. utilization circuit;

3. An electroniesignalstorage system comprisinga storage tube having an; evacuated envelope, an electron gun in said envelope,- said gun having means to produce abeam.ofconstantintensity, an-electric charge storage element in said envelope disposed in the path of said beam, afirst beamdeflectingmeans in'said envelope operable to sweepsaidbeam along .a=basic scanning path, a second beam deflecting. means in said envelope operable to laterallydeflect said. beam.- from' itsbasic scanning path, an input circuit having high and low band pass systems, an external beam sweep generator Whose output is connected. to-said' basic beam deflecting means tosweep'the beam with constant-velocity along its basic scanning path, aconnection from the high band passing means to the output of'said basic beamsweeping means, a connection fromthe low band. passing;meansto said lateral deflecting meansdn said tubetand azconductive output plate capacitively coupled to said storage member.

References; Citediin .the' file of. this patent 

